This is a multidisciplinary study aimed at continuing the development and clinical testing of devices to provide lower limb cancer amputees with sensory feedback from their prosthesis. Based on the previous work on this project the investigators believe that sensory feedback of the type proposed will materially improve the quality of life of lower limb cancer amputees by allowing them: a) To more quickly learn to use their prosthesis and to optimize their gait and balance, b) to more easily walk on soft, uneven and poorly illuminated terrain, c) to adapt more successfully to their changed life. This study will also produce data on the long-term effects of peripheral nerve stimulation on stump pain and circulation problems. In addition, the existing patient population with implanted peripheral nerve stimulation presents a unique opportunity to study sensory physiological phenomena. Previous work has demonstrated the feasibility of multichannel (7) implanted inductive coupled peripheral nerve stimulation. It is proposed to develop and evaluate a series of multichannel sensory feedback systems. It is also proposed to continue to develop and evaluate the single-channel systems of the initial grant period. Evaluation of the device effectiveness involves a research team of orthopedic surgeons, bioengineers, physical therapists, specialists in orthotics and prostheses, psychologists and nurses, each analyzing the patients' reactions to the devices in special laboratory tests and in a day-to-day living setting.